Association between body mass index and cardiovascular disease mortality in east Asians and south Asians: pooled analysis of prospective data from the Asia Cohort Consortium

Abstract

Objective: To evaluate the association between body mass index and mortality from overall cardiovascular disease and specific subtypes of cardiovascular disease in east and south Asians.

Design: Pooled analyses of 20 prospective cohorts in Asia, including data from 835,082 east Asians and 289,815 south Asians. Cohorts were identified through a systematic search of the literature in early 2008, followed by a survey that was sent to each cohort to assess data availability.

Setting: General populations in east Asia (China, Taiwan, Singapore, Japan, and Korea) and south Asia (India and Bangladesh).

Participants: 1,124,897 men and women (mean age 53.4 years at baseline).

Main outcome measures: Risk of death from overall cardiovascular disease, coronary heart disease, stroke, and (in east Asians only) stroke subtypes.

Results: 49,184 cardiovascular deaths (40,791 in east Asians and 8393 in south Asians) were identified during a mean follow-up of 9.7 years. East Asians with a body mass index of 25 or above had a raised risk of death from overall cardiovascular disease, compared with the reference range of body mass index (values 22.5-24.9; hazard ratio 1.09 (95% confidence interval 1.03 to 1.15), 1.27 (1.20 to 1.35), 1.59 (1.43 to 1.76), 1.74 (1.47 to 2.06), and 1.97 (1.44 to 2.71) for body mass index ranges 25.0-27.4, 27.5-29.9, 30.0-32.4, 32.5-34.9, and 35.0-50.0, respectively). This association was similar for risk of death from coronary heart disease and ischaemic stroke; for haemorrhagic stroke, the risk of death was higher at body mass index values of 27.5 and above. Elevated risk of death from cardiovascular disease was also observed at lower categories of body mass index (hazard ratio 1.19 (95% confidence interval 1.02 to 1.39) and 2.16 (1.37 to 3.40) for body mass index ranges 15.0-17.4 and <15.0, respectively), compared with the reference range. In south Asians, the association between body mass index and mortality from cardiovascular disease was less pronounced than that in east Asians. South Asians had an increased risk of death observed for coronary heart disease only in individuals with a body mass index greater than 35 (hazard ratio 1.90, 95% confidence interval 1.15 to 3.12).

Conclusions: Body mass index shows a U shaped association with death from overall cardiovascular disease among east Asians: increased risk of death from cardiovascular disease is observed at lower and higher ranges of body mass index. A high body mass index is a risk factor for mortality from overall cardiovascular disease and for specific diseases, including coronary heart disease, ischaemic stroke, and haemorrhagic stroke in east Asians. Higher body mass index is a weak risk factor for mortality from cardiovascular disease in south Asians.

Fig 1 Association between BMI and CVD mortality in east Asians and south Asians. Analyses for the calculation of hazard ratios were adjusted for baseline age, sex, cigarette smoking, alcohol consumption, educational attainment, marital status, urban residence, and baseline status of cancer. All analyses excluded first three years of follow-up

Fig 2 Subgroup analyses for the association between high BMI values (≥25) and CVD mortality in east Asians. Hazard ratios were estimated in comparison to normal BMI values (18.5-24.9), with adjustments for baseline age, sex, cigarette smoking, alcohol consumption, educational, marital status, urban residence, and baseline status of cancer, except for the stratifying variable. All analyses excluded first three years of follow-up. *Analyses excluded people with missing information on history of CVD and data from the Radiation Effects Research Foundation cohort, three Prefecture Cohort Study Aichi, and Shanghai Cohort Study, which did not have data on previous diagnoses of CHD and stroke

Fig 3 Subgroup analyses for the association between low BMI values (15-18.4) and CVD mortality in east Asians. Hazard ratios were estimated in comparison to normal BMI (18.5-24.9), with adjustments for baseline age, sex, cigarette smoking, alcohol consumption, educational attainment, marital status, urban residence, and baseline status of cancer, except for the stratifying variable. All analyses excluded first three years of follow-up. *Analyses excluded people with missing information on history of CVD and data from the Radiation Effects Research Foundation cohort, three Prefecture Cohort Study Aichi, and Shanghai Cohort Study, which did not have data on previous diagnoses of CHD and stroke

Fig 4 Subgroup analyses for the association between high BMI values (≥25) and CVD mortality in south Asians. Hazard ratios were estimated in comparison to normal BMI (18.5-24.9), with adjustments for baseline age, sex, cigarette smoking, alcohol consumption, educational attainment, marital status, urban residence, and baseline status of cancer, except for the stratifying variable. All analyses excluded first three years of follow-up. *Analyses excluded people with missing information on history of CVD and data from Mumbai cohort, which did not have information on previous diagnoses of stroke, CHD, and hypertension

Fig 5 Subgroup analyses for the association between low BMI values (15-18.4) and CVD mortality in south Asians. Hazard ratios were estimated in comparison to normal BMI (18.5-24.9), with adjustments for baseline age, sex, cigarette smoking, alcohol consumption, educational attainment, marital status, urban residence, and baseline status of cancer, except for the stratifying variable. All analyses excluded first three years of follow-up. *Analyses excluded people with missing information on history of CVD and data from Mumbai cohort, which did not have information on previous diagnoses of stroke, CHD, and hypertension